how do I do an update to my macbook

How to Upgrade  macOS:

The macOS version you can upgrade to depends on the model and year of your Mac.

Click the  (Apple) menu at the top left of your screen and choose About This Mac. 

❗️ – IMPORTANT – Backup your data. (You’ve been warned.)

Learn How to Back up your Mac with Time Machine:

https://support.apple.com/en-us/HT201250

❗️ – IMPORTANT – Your 32-bit apps won’t work in Catalina or Big Sur.

https://support.apple.com/en-us/HT208436

Use this free utility to check the compatibility of your apps:

St. Claire Software – Go64: https://www.stclairsoft.com/Go64/

🖥 – Check compatibility of your Mac with newer versions of macOS.

https://support.apple.com/en-us/HT201475

✅ - Using Safari only, download the macOS upgrade installer:

Click > High Sierra, Mojave, Catalina or Big Sur.

EDIT - How to manually update apps on your Mac

1. Open the App Store.
2. In the sidebar, click Updates.
3. Click Update next to an app to update only that app, or click Update All.